Utilizing Artificial Intelligence and Chat Generative Pretrained Transformer to Answer Questions About Clinical Scenarios in Neuroanesthesiology

OBJECTIVE

We tested the ability of chat generative pretrained transformer (ChatGPT), an artificial intelligence chatbot, to answer questions relevant to scenarios covered in 3 clinical guidelines, published by the Society for Neuroscience in Anesthesiology and Critical Care (SNACC), which has published management guidelines: endovascular treatment of stroke, perioperative stroke (Stroke), and care of patients undergoing complex spine surgery (Spine).

METHODS

Four neuroanesthesiologists independently assessed whether ChatGPT could apply 52 high-quality recommendations (HQRs) included in the 3 SNACC guidelines. HQRs were deemed present in the ChatGPT responses if noted by at least 3 of the 4 reviewers. Reviewers also identified incorrect references, potentially harmful recommendations, and whether ChatGPT cited the SNACC guidelines.

RESULTS

The overall reviewer agreement for the presence of HQRs in the ChatGPT answers ranged from 0% to 100%. Only 4 of 52 (8%) HQRs were deemed present by at least 3 of the 4 reviewers after 5 generic questions, and 23 (44%) HQRs were deemed present after at least 1 additional targeted question. Potentially harmful recommendations were identified for each of the 3 clinical scenarios and ChatGPT failed to cite the SNACC guidelines.

CONCLUSIONS

The ChatGPT answers were open to human interpretation regarding whether the responses included the HQRs. Though targeted questions resulted in the inclusion of more HQRs than generic questions, fewer than 50% of HQRs were noted even after targeted questions. This suggests that ChatGPT should not currently be considered a reliable source of information for clinical decision-making. Future iterations of ChatGPT may refine algorithms to improve its reliability as a source of clinical information.

Association between vitamin D and C-reactive protein level in post-COVID recovery period

Background: Severe acute respiratory distress syndrome coronavirus 2 pandemic shows a spectrum of symptoms and complications which are variably dependent on individual’s immune status. Vitamin D deficiency, often preexisting, causes poor prognosis in the post-COVID recovery phase of the survivors characterized by increased C-reactive protein (CRP) and decreased D-dimer levels. Aims and Objectives: The aims of this study were to find any correlation exists between vitamin D level and inflammatory marker CRP and D-dimer in post-COVID period. Materials and Methods: Seventy post-COVID recovery patients from the follow-up medicine outpatient department of College of Medicine and Sagore Dutta Hospital were tested for vitamin D, D-dimer, and serum CRP levels. Results: CRP levels of patients with lower vitamin D level (<20 ng/ml) were significantly higher (P<0.001) than the patients with higher vitamin D level. The D-dimer levels of vitamin D deficient group found to be significantly higher than the other group. There is statistically significant negative correlation found between CRP and vitamin D level and significant positive correlation has been found between D-dimer and vitamin D (P<0.001). Conclusion: Vitamin D may have an important role in recovery stage of COVID patients.

Injectable Adhesive Hydrogels for Soft tissue Reconstruction: A Materials Chemistry Perspective

Injectable bioadhesives offer several advantages over conventional staples and sutures in surgery to seal and close incisions or wounds. Despite the growing research in recent years few injectable bioadhesives are available for clinical use. This review summarizes the key chemical features that enable the development and improvements in the use of polymeric injectable hydrogels as bioadhesives or sealants, their design requirements, the gelation mechanism, synthesis routes, and the role of adhesion mechanisms and strategies in different biomedical applications. It is envisaged that developing a deep understanding of the underlying materials chemistry principles will enable researchers to effectively translate bioadhesive technologies into clinically-relevant products.

Can paraoxonase activity serve as a comparable marker than high density lipoprotein in the follow-up of patients of coronary artery disease?

Funding Acknowledgements

Type of funding sources: None.

Background

Human serum paraoxonase (PON1) produced by the liver and residing almost exclusively on high density lipoproteins (HDL), has been demonstrated to prevent the oxidation of low density lipoprotein (LDL), which is  the central initiating factor in the causation of atherosclerosis. (1,2) Thus, PON1 along with HDL, plays an important role in the pathophysiology of atherosclerosis and consequently coronary artery disease. Statins are commonly used in clinical practice for the management of dyslipidemia , a known risk factor for coronary artery disease (CAD).Keeping this in mind,  it was deemed necessary to set up an observational study to explore whether the changes in PON1 activity after 3 months of statin therapy could help in the follow up of CAD patients.

Purpose

The purpose of the study was to evaluate the alterations in the PON1 activity along with the concentrations of HDL and LDL in patients of CAD before and after 3 months of statin therapy and to explore whether PON1 can be used as a comparable marker for assessment of the atherosclerotic risk in the follow up of these patients.

Materials and Methods

The study included 30 new patients who were put on statin therapy following the diagnosis of acute coronary syndrome in the Cardiology outpatients department. The activity of PON1 and the lipid profile parameters were estimated before starting statin therapy and again three months later. Patients with co-morbidities like diabetes, chronic kidney disease, chronic liver disease and other cardiac diseases of infectious etiology were excluded from the study. The data thus obtained was compiled and tabulated in Excel and statistically analyzed.

Results

The mean, median and standard deviation of the PON1, LDL and HDL, both before and after starting statin therapy, were calculated and the distribution of the individual parameters were determined. Analysis of the compiled data revealed that there was a statistically significant increase in both PON1 (p &lt; 0.05) and HDL (p &lt; 0.001) and a decrease (p &lt;0.05, also statistically significant) in LDL after 3 months of statin therapy. The results both before and after 3 months of statin therapy are summarised in the table attached.(Table 1)

Conclusion

It may be concluded from the above study that the activity of PON1 may be used to indicate the changes in the lipid profile in the follow up of patients of CAD being treated with statins. It is however necessary to conduct larger, well designed studies in future to explore whether it may be used as a comparable marker better than HDL in the follow up of these patients. Abstract Figure.

Crystal structure of a trigonal polymorph of aqua-dioxidobis(pentane-2,4-dionato-κ2 O,O')uranium(VI)

[UO₂(acac)₂(H₂O)] is constructed from one uran­yl(VI) unit, two monoanionic acetyl­acetonate (acac) ligands and one aqua ligand. The U atom exhibits a UO₇ distorted penta­gonal–bipyramidal coordination geometry; four O atoms from two chelating bidentate acac ligands and one O atom of a aquo ligand (O_w) form the equatorial plane while two uran­yl(VI) O atoms are located at the axial positions.

The title compound, [UO₂(acac)₂(H₂O)] consists of a uran­yl(VI) unit ([O=U=O]²⁺) coordinated to two monoanionic acetyl­acetonate (acac, C₅H₇O₂) ligands and one water mol­ecule. The asymmetric unit includes a one-half of a uranium atom, one oxido ion, one-half of a water mol­ecule and one acac ligand. The coordination about the uranium atom is distorted penta­gonal–bipyramidal. The acac ligands and O_w atom comprise the equatorial plane, while the uranyl O atoms occupy the axial positions. Inter­molecular hydrogen bonding between complexes results in the formation of two-dimensional hexa­gonal void channels along the c-axis direction with a diameter of 6.7 Å. The monoclinic (P2₁/c space group) polymorph was reported by Alcock & Flanders [(1987). Acta Cryst. C43, 1480–1483].

Longitudinal Study of SARS-CoV-2 Antibody Characteristics Using Label-Free Immunoassays

Introduction/Objective

Since the start of the COVID-19 pandemic, much research has focused on the kinetics and magnitude of humoral immune response. With the advantages of monitoring real-time immunoreactions, label-free immunoassay (LFIA) is becoming a powerful tool in serology studies. We have developed LFIAs to measure SARS- CoV-2 antibody avidity and neutralization activity in a cohort of COVID-19 patients and determine if they correlate with antibody concentration. Serial serum samples collected from mild to severe COVID-19 patients were measured out to 8 months post-symptom onset to determine the durability of the neutralizing antibody response.

Methods/Case Report

Based on thin-film interferometry technology, we established a label-free IgG avidity assay and a label-free surrogate virus neutralization test (LF-sVNT). For measurement, sensing probes pre-coated with receptor-binding domain (RBD) of SARS-CoV-2 spike protein are applied to serum samples containing SARS-CoV-2 antibodies. The label-free IgG avidity assay measures the binding strength between RBD and IgG under urea dissociation. The LF-sVNT analyzes the binding ability of RBD to ACE2 after neutralizing RBD with antibodies.

Results (if a Case Study enter NA)

IgG avidity indices and neutralizing antibody titers (IC50) were determined from serum samples (n=246) from COVID-19 patients (n=113). IgG concentrations were measured using a fluorescent immunoassay. The neutralizing antibody titers showed a weak correlation with IgG concentrations and no correlation with IgG avidity indices. Over the time course up to 8 months post-symptom onset, IgG concentrations and neutralizing antibody titers presented similar trends: an initial rise, plateau and then in some cases a gradual decline after 40 days. The IgG avidity indices, in the same cases, plateaued after the initial rise.

Conclusion

The results demonstrated that LFIA could be used an excellent solution in the determination of SARS- CoV-2 antibody characteristics. The study found that IgG concentration and neutralizing antibody titer declined over time, while IgG avidity index remained constant after reaching a plateau. The decline of antibody neutralization activity can be attributed to the reduction in antibody quantity rather than the deterioration of antibody quality, as measured by antibody avidity.

CO release from Mn(i)-based photoCORMs with single photons in the phototherapeutic region

Both the instrumentation required for two photon excitation (TPE) and tissue damage possibility by high intensity laser lights could impede TPE-induced CO delivery in hospital settings. Herein we report two Mn(i)-based photoCORMs with a fac-{Mn(CO)₃} moiety that exhibit facile CO release upon simple exposure to light within the phototherapeutic region (no TPE required).

Sex Hormones, Metabolic Status, and Obesity in Female Patients with Acne Vulgaris Along with Clinical Correlation: An Observational Cross-Sectional Study

Background:

Acne vulgaris is a common dermatological disorder. Several hormones are suspected to play a role in its etiopathogenesis.

Aims and Objectives:

The aim of this study was to analyze the role of sex-hormones, metabolic status, and obesity in acne vulgaris and correlate with its severity and symptom load.

Materials and Methods:

This cross-sectional observational study included 89 female patients with acne vulgaris and certain phenotypic markers such as prepubertal onset, late-onset, persistent course, hirsutism, acanthosis nigricans, acrochordons, premenstrual flare, and diminished response to isotretinoin; suggestive of an underlying hormonal pathology. All patients were subjected to physical examination to rule out obesity and metabolic syndrome along with serum biochemistry to detect sex hormones (testosterone, progesterone, estrogen), serum insulin and insulin resistance (HOMA-IR) and lipid profile.

Results:

Among 89 patients (mean age 21.3 ± 5.3 years), 34.8% presented with late-onset/persistent/pre-pubertal acne, 33.7% presented with premenstrual flare and 28.2% presented with hirsutism. Hormonal analysis revealed elevated testosterone and progesterone with low estrogen across all categories of patients. Testosterone was significantly elevated even in mild acne. Serum lipid profile was altered significantly only in hirsute females. In total, 36% and 20.2% patients presented with metabolic syndrome and obesity, respectively; however, neither was associated with severity of acne.

Conclusion:

Sex-hormones, serum lipids, metabolic status, and body mass index are altered in acne vulgaris. All acne patients with endocrine markers should be evaluated for sex-hormones irrespective of severity and symptom load, whereas hirsutism may be regarded as clinical marker of lipid abnormalities. Metabolic syndrome and obesity do not seem to be directly correlated with acne severity. Thus, anti-androgens may be considered as adjuvant therapy in these patients, not responding to conventional therapy.

Polymers and Composites Derived from Castor Oil as Sustainable Materials and Degradable Biomaterials: Current Status and Emerging Trends

Recent years have seen rapid growth in utilizing vegetable oils to derive a wide variety of polymers to replace petroleum-based polymers for minimizing environmental impact. Nonedible castor oil (CO) can be extracted from castor plants that grow easily, even in an arid land. CO is a promising source for developing several polymers such as polyurethanes, polyesters, polyamides, and epoxy-polymers. Several synthesis routes have been developed, and distinct properties of polymers have been studied for industrial applications. Furthermore, fillers and fibers, including nanomaterials, have been incorporated in these polymers for enhancing their physical, thermal, and mechanical properties. This review highlights the development of CO-based polymers and their composites with attractive properties for industrial and biomedical applications. Recent advancements in CO-based polymers and their composites are presented along with a discussion on future opportunities for further developments in diverse applications.

Structural studies of immunomodulatory (1 → 3)-, (1 → 4)-α glucan from an edible mushroom Polyporus grammocephalus

A water soluble polysaccharide (PGPS) with molecular weight ~ 1.4 × 10⁵ Da was isolated by alkali treatment from an edible mushroom Polyporus grammocephalus and purified by gel chromatography using sepharose-6B column. Monosaccharide analysis revealed that PGPS was made up of glucose only. PGPS contained (1 → 3)-α-D-Glcp and (1 → 4)-α-D-Glcp moieties in a molar ratio of nearly 1:2. Through a series of chemical and spectroscopic (1D/2D NMR) investigations, the repeating unit of the glucan was established as: →3)-α-D-Glcp(1 → [4)-α-D-Glcp(1]₂→ This α-glucan was observed to stimulate some prime components of immune system, namely, macrophages, splenocytes, and thymocytes.

COVID-19 outbreak: Migration, effects on society, global environment and prevention

The COVID-19 pandemic is considered as the most crucial global health calamity of the century and the greatest challenge that the humankind faced since the 2nd World War. In December 2019, a new infectious respiratory disease emerged in Wuhan, Hubei province, China and was named by the World Health Organization as COVID-19 (coronavirus disease 2019). A new class of corona virus, known as SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has been found to be responsible for occurrence of this disease. As far as the history of human civilization is concerned there are instances of severe outbreaks of diseases caused by a number of viruses. According to the report of the World Health Organization (WHO as of April 18 2020), the current outbreak of COVID-19, has affected over 2164111 people and killed more than 146,198 people in more than 200 countries throughout the world. Till now there is no report of any clinically approved antiviral drugs or vaccines that are effective against COVID-19. It has rapidly spread around the world, posing enormous health, economic, environmental and social challenges to the entire human population. The coronavirus outbreak is severely disrupting the global economy. Almost all the nations are struggling to slow down the transmission of the disease by testing & treating patients, quarantining suspected persons through contact tracing, restricting large gatherings, maintaining complete or partial lock down etc. This paper describes the impact of COVID-19 on society and global environment, and the possible ways in which the disease can be controlled has also been discussed therein.

Room temperature blooming of CeO2 3D nanoflowers under sonication and catalytic efficacy towards CO conversion

Carbon monoxide (CO), being a highly toxic gas, bears hazardous effects on human health and contributes majorly to environmental pollution. It is mostly produced by automobile exhausts and incomplete combustion of carbon-containing substances. Thus, the development of catalysts for CO conversion is highly imperative and has always gained interest for real field applications. Besides the high oxygen storage capacity and facile transitions between oxidation states, the huge abundance of cerium on earth makes CeO₂ a low-cost and highly effective alternative to noble metal catalysts for CO oxidation. The present work delineates the room temperature synthesis of flower-shaped 3D CeO₂ nanostructures using a sonication-assisted simple synthesis method within 2 hours under the pivotal importance of a structure-directing agent, polyvinylpyrrolidone (PVP). The bifunctional contributions of PVP as a surfactant and as a capping agent are discussed with a plausible mechanism. The method leading to the formation of hierarchical CeO₂ nanoflowers provides an appreciable surface area of 132.69 cm² g⁻¹. The morphological and structural characterizations of the catalyst were thoroughly investigated using FESEM, TEM, XRD, UV-visible spectroscopy, photoluminescence spectroscopy, FTIR spectroscopy and X-ray photoelectron spectroscopy. The structural efficacies of flower-like CeO₂ nanostructures have also been correlated to the narrowing of the band gap and the generation of the corresponding oxygen vacancies, resulting in surface catalytic properties towards 80% conversion of CO.

Carbon monoxide (CO), being a highly toxic gas, bears hazardous effects on human health and contributes majorly to environmental pollution.

Enhanced Bactericidal Effects of Pyrazinamide Toward Mycobacterium smegmatis and Mycobacterium tuberculosis upon Conjugation to a {Au(I)-triphenylphosphine}+ Moiety

As part of the quest for new gold drugs, we have explored the efficacy of three gold complexes derived from the tuberculosis drug pyrazinamide (PZA), namely, the gold(I) complex [Au(PPh₃)(PZA)]OTf (1, OTf = trifluoromethanesulfonate) and two gold(III) complexes [Au(PZA)Cl₂] (2) and [Au(PZO)Cl₂] (3, PZO = pyrazinoic acid, the metabolic product of PZA) against two mycobacteria, Mycobacterium tuberculosis and Mycobacterium smegmatis. Only complex 1 with the {Au(PPh₃)}⁺ moiety exhibits significant bactericidal activity against both strains. In the presence of thiols, 1 gives rise to free PZA and {Au(PPh₃)}-thiol polymeric species. A combination of PZA and the {Au(PPh₃)}-thiol polymeric species appears to lead to enhanced efficacy of 1 against M. tuberculosis.

In situ unsupervised learning using stochastic switching in magneto-electric magnetic tunnel junctions

Spiking neural networks (SNNs) offer a bio-plausible and potentially power-efficient alternative to conventional deep learning. Although there has been progress towards implementing SNN functionalities in custom CMOS-based hardware using beyond Von Neumann architectures, the power-efficiency of the human brain has remained elusive. This has necessitated investigations of novel material systems which can efficiently mimic the functional units of SNNs, such as neurons and synapses. In this paper, we present a magnetoelectric-magnetic tunnel junction (ME-MTJ) device as a synapse. We arrange these synapses in a crossbar fashion and perform in situ unsupervised learning. We leverage the capacitive nature of write-ports in ME-MTJs, wherein by applying appropriately shaped voltage pulses across the write-port, the ME-MTJ can be switched in a probabilistic manner. We further exploit the sigmoidal switching characteristics of ME-MTJ to tune the synapses to follow the well-known spike timing-dependent plasticity (STDP) rule in a stochastic fashion. Finally, we use the stochastic STDP rule in ME-MTJ synapses to simulate a two-layered SNN to perform image classification tasks on a handwritten digit dataset. Thus, the capacitive write-port and the decoupled-nature of read-write path of ME-MTJs allow us to construct a transistor-less crossbar, suitable for energy-efficient implementation of in situ learning in SNNs. This article is part of the theme issue 'Harmonizing energy-autonomous computing and intelligence'.

Spontaneous Resolution by Crystallization of an Octanuclear Iron(III) Complex Using Only Racemic Reagents

The P and M enantiomers of the octanuclear [Fe₈ (μ₄ -O)₄ (μ-4-Cl-pz)₁₂ Cl₄ ] complex, having T symmetry, were resolved by temporary substitution of chloride ligands by racemic 4-^s Bu-phenolates and subsequent crystallization, where the (S)- and (R)-phenolates coordinate selectively to the M and P complexes, respectively. The complexes were characterized by circular dichroism analysis and X-ray structure determination. This work constitutes a rare example of enantiomeric recognition resulting in spontaneous resolution upon crystallization.

Effect of bovine serum albumin on tartrate-modified manganese ferrite nano hollow spheres: spectroscopic and toxicity study

The emerging category of magneto-fluorescent tartrate-modified MnFe₂O₄ nano hollow spheres (T-MnFe₂O₄ NHSs) can be considered as promising candidates for biomedical applications. The interaction of bovine serum albumin (BSA) with T-MnFe₂O₄ NHSs has been studied using several spectroscopic techniques, which suggest that the interaction occurs by an electrostatic mechanism. Furthermore, BSA enhances the charge transfer transition from the tartrate ligand to the metal ions along with the d-d transition of Fe³⁺ ions on NHSs surfaces at different pH. Very strong salt bridge formation occurs between the lysine of the BSA surface and the tartrate in basic medium (pH 10), followed by the acidic (pH 3) and neutral medium (pH 7), respectively. Systematic fluorescence microscopic analysis reveals that BSA significantly enhances the contrast of T-MnFe₂O₄ NHSs in UV and blue light excitation because of the extended charge transfer from BSA to T-MnFe₂O₄ NHSs. Our report demonstrates great potential in the field of nanotechnology and biomedical applications. In vitro toxicity analysis using RAW 264.7 celline and in vivo studies on Wister rats revealed that the T-MnFe₂O₄ NHSs are benign. Furthermore, T-MnFe₂O₄ NHSs also appear to be an antimicrobial agent. Therefore, T-MnFe₂O₄ NHSs can be explored for future therapeutic applications.

Facet-Dependent Photodegradation of Methylene Blue Using Pristine CeO2 Nanostructures

This work comprises the shape- and facet-dependent catalytic efficacies of different morphologies of CeO₂, namely, hexagonal, rectangular, and square. The formation of different shapes of CeO₂ is controlled using polyvinyl pyrrolidone as a surfactant. The surface reactivity of formation of differently exposed CeO₂ facets is thoroughly investigated using UV-visible, photoluminescence, Raman, and X-ray photoelectron spectroscopies. A correlation between the growth of a surface-reactive facet and the corresponding oxygen vacancies is also established. Considering the tremendous contamination, caused by the textile effluents, the present study articulates the facet-dependent photocatalytic activities of pristine CeO₂ for complete degradation of methylene blue within 175 min. The observed degradation time deploying pristine CeO₂ as a catalyst is the shortest to be reported in the literature to our best knowledge.

Simultaneous nitrosylation and N-nitrosation of a Ni-thiolate model complex of Ni-containing SOD

Nitric oxide (NO) is used as a substrate analogue/spectroscopic probe of metal sites that bind and activate oxygen and its derivatives. To assess the interaction of superoxide with the Ni center in Ni-containing superoxide dismutase (NiSOD), we studied the reaction of NO⁺ and NO with the model complex, Et₄N[Ni(nmp)(SPh-o-NH₂-p-CF₃)] (1; nmp^2- = dianion of N-(2-mercaptoethyl)picolinamide; ^-SPh-o-NH₂-p-CF₃ = 2-amino-4-(trifluoromethyl)benzenethiolate) and its oxidized analogue 1^ox , respectively. The ultimate products of these reactions are the disulfide of ^-SPh-o-NH₂-p-CF₃ and the S,S-bridged tetrameric complex [Ni₄(nmp)₄], a result of S-based redox activity. However, introduction of NO to 1 affords the green dimeric {NiNO}¹⁰ complex (Et₄N)₂[{Ni(κ²-SPh-o-NNO-p-CF₃)(NO)}₂] (2) via NO-induced loss of nmp^2- as the disulfide and N-nitrosation of the aromatic thiolate. Complex 2 was characterized by X-ray crystallography and several spectroscopies. These measurements are in-line with other tetrahedral complexes in the {NiNO}¹⁰ classification. In contrast to the established stability of this metal-nitrosyl class, the Ni-NO bond of 2 is labile and release of NO from this unit was quantified by trapping the NO with a Co^II-porphyrin (70-80% yield). In the process, the Ni ends up coordinated by two o-nitrosaminobenzenethiolato ligands to result in the structurally characterized trans-(Et₄N)₂[Ni(SPh-o-NNO-p-CF₃)₂] (3), likely by a disproportionation mechanism. The isolation and characterization of 2 and 3 suggest that: (i) the strongly donating thiolates dominate the electronic structure of Ni-nitrosyls that result in less covalent Ni-NO bonds, and (ii) superoxide undergoes disproportionation via an outer-sphere mechanism in NiSOD as complexes in the {NiNO}^9/8 state have yet to be isolated.

Toward Fast Neural Computing using All-Photonic Phase Change Spiking Neurons

The rapid growth of brain-inspired computing coupled with the inefficiencies in the CMOS implementations of neuromrphic systems has led to intense exploration of efficient hardware implementations of the functional units of the brain, namely, neurons and synapses. However, efforts have largely been invested in implementations in the electrical domain with potential limitations of switching speed, packing density of large integrated systems and interconnect losses. As an alternative, neuromorphic engineering in the photonic domain has recently gained attention. In this work, we propose a purely photonic operation of an Integrate-and-Fire Spiking neuron, based on the phase change dynamics of Ge₂Sb₂Te₅ (GST) embedded on top of a microring resonator, which alleviates the energy constraints of PCMs in electrical domain. We also show that such a neuron can be potentially integrated with on-chip synapses into an all-Photonic Spiking Neural network inferencing framework which promises to be ultrafast and can potentially offer a large operating bandwidth.

Cationic Au(I) complexes with aryl-benzothiazoles and their antibacterial activity

Two cationic Au(I) complexes derived from aryl-benzothiazoles, namely [(PPh₃)Au(pbt)](OTf) (1) and [(PPh₃)Au(qbt)](OTf) (2) (where pbt = 2‑(pyridyl)benzothiazole and qbt = (quinolyl)benzothiazole, and OTf^- = trifluoromethanesulfonate anion), have been synthesized and structurally characterized by X-ray crystallography. Both complexes exhibit strong antibacterial effects against Gram-negative bacteria such as Acinetobacter baumannii and Pseudomonas Aeruginosa. Results of examination of the reactions of 1 and 2 indicate that these cationic Au(I) complexes rapidly cross the bacterial membrane and exert drug action by disrupting cellular function(s) through binding of cytosolic thiol-containing peptides (such as glutathione) and proteins to the highly reactive (PPh₃)Au⁺ intermediate formed upon in situ dissociation of pbt or qbt.

CO-Induced apoptotic death of colorectal cancer cells by a luminescent photoCORM grafted on biocompatible carboxymethyl chitosan

A photo-active luminescent rhenium carbonyl complex namely, [Re(CO)₃(phen)(pyAl)](CF₃SO₃) was grafted on a biocompatible carboxymethyl chitosan (CMC) matrix through Schiff base condensation reaction. The light-induced CO delivery from ReCMC has been shown to eradicate human colorectal adenocarcinoma cells (HT-29) very efficiently in a dose-dependent fashion. The onset of CO-induced apoptosis was realized by caspase-3,-7 detection aided by fluorescence confocal microscopy. ReCMC represents a unique example of a biocompatible and biodegradable antineoplastic agent that could find its use in cancer photopharmacology.

Two structurally diverse Zn-based coordination polymers with excellent antibacterial activity

Two novel Zn-based coordination polymers with unique structural properties display an exceptional antibacterial activity against Gram-positive and Gram-negative bacteria.

Synthesis and structures of photoactive rhenium carbonyl complexes derived from 2-(pyridin-2-yl)-1,3-benzothiazole, 2-(quinolin-2-yl)-1,3-benzothiazole and 1,10-phenanthroline

Carbon monoxide (CO) has recently been identified as a gaseous signaling molecule that exerts various salutary effects in mammalian pathophysiology. Photoactive metal carbonyl complexes (photoCORMs) are ideal exogenous candidates for more controllable and site-specific CO delivery compared to gaseous CO. Along this line, our group has been engaged for the past few years in developing group-7-based photoCORMs towards the efficient eradication of various malignant cells. Moreover, several such complexes can be tracked within cancerous cells by virtue of their luminescence. The inherent luminecscent nature of some photoCORMs and the change in emission wavelength upon CO release also provide a covenient means to track the entry of the prodrug and, in some cases, both the entry and CO release from the prodrug. In continuation of the research circumscribing the development of trackable photoCORMs and also to graft such molecules covalently to conventional delivery vehicles, we report herein the synthesis and structures of three rhenium carbonyl complexes, namely, fac-tricarbonyl[2-(pyridin-2-yl)-1,3-benzothiazole-κ²N,N'](4-vinylpyridine-κN)rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₂H₈N₂S)(CO)₃](CF₃SO₃), (1), fac-tricarbonyl[2-(quinolin-2-yl)-1,3-benzothiazole-κ²N,N'](4-vinylpyridine-κN)rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₆H₁₀N₂S)(CO)₃](CF₃SO₃), (2), and fac-tricarbonyl[1,10-phenanthroline-κ²N,N'](4-vinylpyridine-κN)rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₂H₈N₂)(CO)₃](CF₃SO₃), (3). In all three complexes, the Re^I center resides in a distorted octahedral coordination environment. These complexes exhibit CO release upon exposure to low-power UV light. The apparent CO release rates of the complexes have been measured to assess their comparative CO-donating capacity. The three complexes are highly luminescent and this in turn provides a convenient way to track the entry of the prodrug molecules within biological targets.

Microfluidic step-emulsification in axisymmetric geometry

Biphasic step-emulsification (Z. Li et al., Lab Chip, 2015, 15, 1023) is a promising microfluidic technique for high-throughput production of μm and sub-μm highly monodisperse droplets. The step-emulsifier consists of a shallow (Hele-Shaw) microchannel operating with two co-flowing immiscible liquids and an abrupt expansion (i.e., step) to a deep and wide reservoir. Under certain conditions the confined stream of the disperse phase, engulfed by the co-flowing continuous phase, breaks into small highly monodisperse droplets at the step. Theoretical investigation of the corresponding hydrodynamics is complicated due to the complex geometry of the planar device, calling for numerical approaches. However, direct numerical simulations of the three dimensional surface-tension-dominated biphasic flows in confined geometries are computationally expensive. In the present paper we study a model problem of axisymmetric step-emulsification. This setup consists of a stable core-annular biphasic flow in a cylindrical capillary tube connected co-axially to a reservoir tube of a larger diameter through a sudden expansion mimicking the edge of the planar step-emulsifier. We demonstrate that the axisymmetric setup exhibits similar regimes of droplet generation to the planar device. A detailed parametric study of the underlying hydrodynamics is feasible via inexpensive (two dimensional) simulations owing to the axial symmetry. The phase diagram quantifying the different regimes of droplet generation in terms of governing dimensionless parameters is presented. We show that in qualitative agreement with experiments in planar devices, the size of the droplets generated in the step-emulsification regime is independent of the capillary number and almost insensitive to the viscosity ratio. These findings confirm that the step-emulsification regime is solely controlled by surface tension. The numerical predictions are in excellent agreement with in-house experiments with the axisymmetric step-emulsifier.

Eradication of HT-29 colorectal adenocarcinoma cells by controlled photorelease of CO from a CO-releasing polymer (photoCORP-1) triggered by visible light through an optical fiber-based device

The gaseous signaling molecule carbon monoxide (CO) has recently been recognized for its wide range of physiological activity as well as its antineoplastic properties. However, site-specific delivery of this noxious gas presents a major challenge in hospital settings. In this work, a visible light-sensitive CO-releasing molecule (photoCORM) derived from manganese(I) and 2-(quinolyl)benzothiazole (qbt) namely, [Mn(CO)₃(qbt)(4-vpy)](CF₃SO₃) (1), has been co-polymerized within a gas-permeable HEMA/EGDMA hydrogel. The resulting photoactive CO-releasing polymer (photoCORP-1) incorporates 1 such that neither the carbonyl complex nor its photoproduct(s) exits the polymer at any time. The material can be triggered to photorelease CO remotely by low-power broadband visible light (<1mWcm^-2) with the aid of fiber optics technology. The CO photorelease rates of photoCORP-1 (determined by spectrophotometry) can be modulated by both the concentration of 1 in the hydrogel and the intensity of the light. A CO-delivery device has been assembled to deliver CO to a suspension of human colorectal adenocarcinoma cells (HT-29) under the control of visible light and the extent of CO-induced apoptotic death of the cancer cells has been determined via Annexin V/Propidium iodide stain and flow cytometry. This photoactive CO-releasing polymer could find use in delivering controlled doses of CO to cellular targets such as malignant tissues in remote parts of the body.

Five- and Six-Coordinated Silver(I) Complexes Derived from 2,6-(Pyridyl)iminodiadamantanes: Sustained Release of Bioactive Silver toward Bacterial Eradication

Silver(I) complexes of two designed tridentate ligands, namely, 2,6-(pyridyl)iminoditriazaadamantane (pydTAm) and 2,6-(pyridyl)iminodiadamantane (pydAm), have been synthesized and structurally characterized. [Ag(pydTAm)₂](CF₃SO₃) (1), the hitherto unknown mer isomer of a silver(I) octahedral complex, crystallizes in a highly symmetric body-centered cubic I4̅3m space group. Quite in contrast, the Ag^I center in the analogous [Ag(pydAm)₂](CF₃SO₃) (2) complex resides in a trigonal-bipyramidal geometry and crystallizes in a triclinic P1̅ space group with two crystallographically independent molecules in the asymmetric unit. Complex 1 exhibits exceptional solubility in aqueous media and leads to the efficient eradication of several bacterial strains upon sustained release of bioactive silver.